4WDing in Winter

4WD Tips      June 24, 2013      David Wilson

Well we’re well and truly in the depths of Winter now having just passed the solstice. One thing that is obvious here in Adelaide at the moment and surrounding rural areas is there’s been a LOT of rain about which will give the cockys something to be thankful for (let’s hope that converts into a massive grain harvest this Summer). I heard this morning reported that so much rain had fallen over the weekend that around 17kms north of Jamestown the RM Williams Way had been closed due to flooding. That doesn’t happen very often, so it begs the question what to do when you see the wet stuff covering a road?

The answer is a little dependent on what the road base might be. For example the RMW Way is a bitumen road and provided the force of the water hasn’t been too great, it would be reasonable to expect that the bitumen will still be there without damage and still be navigable. Depth then becomes the issue and a quick consult with the roadside depth marker is in order. Anything over 250mm will be problematic for most passenger cars and some AWDs. Between 300 and 700mm might be problematic for some 4WDs and anything deeper is likely to be plain stupid and especially if it’s fast flowing.

The issue is where expensive and vital driveline and electronics components might lie. Differentials are the first thing to go under. You’d like to think there’s a breather tube going up to a higher point off the diff’s valve to prevent water ingress. As we go deeper there’s gearbox, transfer case, alternator, air intake, ECU and a whole lot more that get in the way. Even simple things like headlights, foglights, driving lights and indicators are going to get a dunking which 3-6months later might start playing up, so immersion isn’t usually a good thing.

If you’re tackling an Outback track that’s flooded and the water is sitting on the road, that’s likely to still be the best route to take (of course not if the road’s been officially closed). The temptation is to use the edge of the road that appears less sodden, but the reality is it’ll likely have no substance. Take a 4WD out there and it’ll sink faster than the fortunes of our current Labor Government(s). The reason the water is there is because the road base is compacted and firm and the moisture can’t percolate through that crust.

First, find your engine air intake and make sure it’s not going to swallow a big gob of mud. A poly tarp makes an effective blind when stretched over the bonnet. Next, dump a lot of tyre pressure. Fifteen minutes now might save you hours later. At 15psi/100kPa (if the track is real bad) your tyre will have a longer print and miraculous flotation. Go no faster than 20-40kph and preferably in LOW range (for best torque) in 2nd to 4th gears (dependent on vehicle). Smooth and steady wins the race with STRAIGHT steering. Slap bang in the middle is where you want to be, remember that’s where the ground is hardest and compact, the verge will likely be bottomless and you’ll bugger up the veg. If you run out of traction dump more air. The object is to maintain progress, so slow and steady wins this race, once the road is clear again, increase the pressures to match your speed. Then use HIGH range again and no faster than 80kph!

drown the gopro 2

Above: Don’t be tempted to rush situations like this. Orange muddy water flying over a bonnet gets into places where the sun doesn’t shine and can cause damage!


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